Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C8/00—Diffusion transfer processes or agents therefor; Photosensitive materials for such processes
  • G03C8/24—Photosensitive materials characterised by the image-receiving section
  • G03C8/243—Toners for the silver image

Definitions

• French Patent No. 879,995 describes a process for the direct production of positives in which the unexposed and, therefore, undevelopable silver halide of an image-wise exposed photographic silver halide emulsion layer is dissolved during or after the development of the negative and is transferred in another image-receiving or transfer layer with which it is in close contact under the catalytic influence of development nuclei that are present in this transfer layer which are capable of precipitating metallic silver from the dissolved silver salt to form a positive image.
• the terms negative and positive are in this case used only in a relative sense, since it is possible by the same process to obtain directly a negative from a negative original.
• This process which is known as a silver salt diffusion process, is used inter alia for high-speed copying in business offices, using a developing apparatus suitable for this purpose.
• the present tendency is to arrange for the entire process to be carried out as quickly as possible, i.e., so that the time of travel through the developing apparatus and thus also the time of contact of the positive with the negative that is required in such a diffusion process should be as short as possible.
• 2(1H -tetrahydropyrimidinethiones can be prepared from N-alkylsubstituted 1,3-propylenediamines and carbon disulfide in a manner analogous to that described by C. F. H. Allen, C. O. Edens and James Van Allan on pages 34 and 35 of Organic Syntheses, vol. 26, published 1946 by John Wiley & Sons, Inc., New York, for the preparation of ethylene thiourea (Z-imidazolidinethione) from ethylenediamine and carbon disulfide.
• 2( lH)-tetrahydropyrimidinethione was described by Arthus E. Baum, in United States Patent No.
• 2(1H)-tetrahydropyrimidinethiones are soluble in water and alkali and are added to the transfer material and/ or to the developer solution in quantities of between 1 and 200 milligrams per square meter of transfer material or per liter of developer.
• Various silver halides and their mixtures such as silver chloride, silver bromide or silver bromoiodide, can be used for the production of the light-sensitive negative material, and the said halides or mixtures can if desired'be optically sensitized in the usual manner.
• All known layerforming substances are to be considered as layer formers for the negative layer, including gelatin, starch, polyvinyl alcohol, cellulose derivatives and the like.
• Paper, and films consisting, for example, of cellulose acetate, cellulose nitrate, polycarbonate, polyethylene terephthalate, polystyrene and others are suitable as the base for the silver halide emulsion layer.
• a base or support consisting of paper or a plastic film is also advantageously used for the positive material.
• other supports such as metal, textile fabric and the like can also be used.
• a layer which contains development nuclei, such as colloidal noble metals or metal sulfides, and, if necessary, a silver halide solvent may be applied to such a support.
• a hydrophilic colloid is advantageously used, such as gelatin, casein, carboxymethyl cellulose, starch, starch ethers, starch esters, galactomannans polymannuronic acids, polymannuronic acid esters, polymannuronic acid amides, polyvinyl alcohol and its derivatives or the like.
• the developer solution can contain a silver halide solvent as well as conventional developer additives, such as preservatives, wetting agents and the like.
• the developer substance can also be added to the negative layer and/or to the positive layer.
• Example 1 A support, for example, a sheet of paper, has applied thereto a solution of the following composition:
• a gelatino-silver chloride layer exposed through an original by reflex copying is developed in a developer having the following composition and brought into contact with the positive:
• Example 2 A sheet of paper is coated as in Example 1 with a layer which contains a white pigment, for example, barium sulfate. To the said layer is then applied a layer having the following composition:
• Gelatin 80 Carboxymethyl cellulose 20 Ag S (colloidal) 0.03 Sodium thiosulphate Water to make 1 liter.
• Example 4 To a sheet of paper is applied a solution having the following composition:
• Gelatin 150 Carboxymethyl cellulose 22' Ag S (colloidal) 0.05 Sodium thiosulphate 60 2(1H)-tetrahydropyrimidinethione 0.03
• This positive material and an exposed negative are each moistened in a developer as in Example 2 and thereafter brought into contact with each other. After a contact time of about 12 seconds, a deep black positive image of the original is obtained.
• the developers may contain any stabilizing agents, anti-fog agents and antioxidants, such as alkali-metal sulphites or salts of hydroxylamine.
• Chemical compounds which can be used as silver halide solvents include, for example, water-soluble thiosulphates, such as alkali-metal thiosulphate, ammonium thiosulphate and alkaline earth thiosulphates.
• An image-receiving material that is insensitive to light which comprises a paper support coated with a layer of a hydrophilic colloidal substance containing development nuclei and containing an amount between about 1 and 200 milligrams per square meter of surface of a 2(1H)-tetrahydropyrimidinethione having the general formula wherein R stands for a radical selected from the group r 5 6 consisting of hydrogen and alkyl radicals containing 1 to in which R is a radical of the group consisting of hydro- 5 carbon atoms. gen and alkyl radicals containing from 1 to 5 carbon 6.
• hydrophilic colloidal substance is selected from the group consisting of gelatin, casein, carboxy 5 References Cited y the Examine! methyl cellulose, starch, starch ethers, starch esters, galac- UNITED STATES PATENTS tomannans, polymannuronic acids, polymannuronic acid esters, polymannuronic acid amides, polyvinyl alcohol 2901351 8/1959 Van ee et a1 260 256'5 and polyvinyl alcohol derivatives. 3017270 1/1962 Tregluus 9629 7.
• aqueous alkaline developer solution containing a developer for silver halides and between 1 and 200 10 FOREIGN TE milligrams per liter of a 2(1H)-tetrahydropyrimidine- 753, 7/ 1956 Great Brltaln- 783,793 10/1957 Great Britain.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Silver Salt Photography Or Processing Solution Therefor (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Publications (1)

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Citations (5)

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• 0
  • BE BE608384D patent/BE608384A/xx unknown
• 1960
  • 1960-09-24 DE DEA35652A patent/DE1124355B/de active Pending
• 1961
  • 1961-09-12 US US137491A patent/US3236642A/en not_active Expired - Lifetime
  • 1961-09-19 CH CH1084661A patent/CH413595A/de unknown
  • 1961-09-22 GB GB34057/61A patent/GB950668A/en not_active Expired

Patent Citations (5)

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